Sten tube

[Karl_T]

This is my Sten receiver tube project. For those not aware, you can buy pieces of old cut up military weapons and rebuild them into semi-auto rifles. In nearly all cases, the receiver is cut up and destroyed on these parts kits. Here's info on the Sten: http://en.wikipedia.org/wiki/Sten. BUT FIRST, you need the project to do the project. I just finished installing a servo motor to drive my index head. Here's everything mounted on the table:

 

[Karl_T]

This is on my Excello 602 CNC knee mill with a Camsoft control. I first reconfigured the control to have a 4rth axis and found the number of encoder counts for one revolution and the number of counts of backlash. With this poor man's setup, the backlash is HUGE - 150 encoder counts - too much for the CNC control to handle. I'll have to add in a Gcode line every time direction in reversed

 

[Karl_T]

Then I found a .pdf print on the web of Sten receiver. First I drew it up with degree of revolution on the 4rth axis. When I got to the cocking slot, I seen that won't work. There are arcs to be cut and you can't have different units on one axis X in inches, A in degrees and get the correct arc. So i re did the control for a 1.5 inch tube to get motion on A in inches of surface movement. At this point I have a first draft of the receiver in Draftsight X64. The white lines are the outline to be cut, blue lines are quadrants of the tube laid out flat (gives reference for the drawing work), the green lines are the tool path for a 1/4inch endmill. I see mistakes in the .pdf, need to work them out, also some work will need to be cut with a 1/8 endmill. I'll lay this out as another layer on the drawing

 

[sd624]

Karl_T I've built a handful of SAS in the past and have two going right now on the workbench. I've just printed out the templates and glued them to the tubes and cut the out by hand on the BP. Your setup looks sweet and will make doing the tube a walk in the park. Keep the pics coming.

 

[ScrapMetal]

I've been contemplating a Sten build myself so will be watching your progress.

Thanks,

-Ron

 

[Karl_T]

OK, today's job... Finished checking drawing against actual parts and made some updates. Then I saved only the 250EM layer from Draftsight to a .dxf file. I opened NCplot and converted from .dxf to Gcode. I see the NCplot webpage now has a free .dxf to Gcode converter. Now I have a Gcode program to test on the mill. I'll order tubing later today and test the code on the mill................... EDIT I can't get paragraphs to work in this forum - everything runs together - how to I separate my text? I put in ... today. Karl

 

[Karl_T]

One more tiny step I'll mention. MEconsultant says to run my 2 flute HSS endmill at 1000 RPM 2.5 IPM I'll plunge at 0.5 IPM

 

[JimDawson]

EDIT I can't get paragraphs to work in this forum - everything runs together - how to I separate my text? I put in ... today. Karl

I just tested it.

Seems to be working now

The admins are working on the site, so a few strange things have happened.

Sorry for the inconvenience.

 

[Karl_T]

I just tested it. Seems to be working now The admins are working on the site, so a few strange things have happened. Sorry for the inconvenience.

Hmmm, FNG doing something wrong.

I just edited in paragraphs in above post. it didn't take, ran it all together again.

Karl Edit, I'm just hitting enter twice to make a paragraph.

 

[JimDawson]

Hmmm, FNG doing something wrong.

I just edited in paragraphs in above post. it didn't take, ran it all together again.

Karl Edit, I'm just hitting enter twice to make a paragraph.

I just edited your post above, it seemed to work OK. I also am hitting enter twice to make a paragraph.

Maybe your browser? I am using Google Chrome. Not sure what the problem is, keyboard issue?